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31.
Tomislav Došli? 《Discrete Mathematics》2008,308(11):2297-2300
The structural theory of matchings is used to establish lower bounds on the number of perfect matchings in n-extendable graphs. It is shown that any such graph on p vertices and q edges contains at least ⌈(n+1)!/4[q-p-(n-1)(2Δ-3)+4]⌉ different perfect matchings, where Δ is the maximum degree of a vertex in G. 相似文献
32.
Tomislav Do?li? 《Journal of mathematical chemistry》2009,45(4):1130-1136
We use some recent results on the existence of long cycles in leapfrog fullerenes to establish new exponential lower bounds
on the number of perfect matchings in such graphs. The new bounds are expressed in terms of Fibonacci numbers. 相似文献
33.
We study decoherence in a simple quantum mechanical model using two approaches. Firstly, we follow the conventional approach to decoherence where one is interested in solving the reduced density matrix from the perturbative master equation. Secondly, we consider our novel correlator approach to decoherence where entropy is generated by neglecting observationally inaccessible correlators. We show that both methods can accurately predict decoherence time scales. However, the perturbative master equation generically suffers from instabilities which prevents us to reliably calculate the system’s total entropy increase. We also discuss the relevance of the results in our quantum mechanical model for interacting field theories. 相似文献
34.
We formulate a holomorphic theory of gravity and study how the holomorphy symmetry alters the two most important singular
solutions of general relativity: black holes and cosmology. We show that typical observers (freely) falling into a holomorphic
black hole do not encounter a curvature singularity. Likewise, typical observers do not experience Big Bang singularity. Unlike
Hermitian gravity (Mantz and Prokopec in , 2008), holomorphic gravity does not respect the reciprocity symmetry and thus it is mainly a toy model for a gravity theory formulated
on complex space-times. Yet it is a model that deserves a closer investigation since in many aspects it resembles Hermitian
gravity and yet calculations are simpler. Our study of light bending and gravitational waves in weak holomorphic gravitational
fields strongly suggests that holomorphic gravity reduces to general relativity at large distance scales. 相似文献
35.
36.
Tomislav P. Živković 《Journal of mathematical chemistry》2011,49(1):35-78
LRM (Low Rank Modification) is a mathematical method that produces eigenvalues and eigenstates of generalized eigenvalue equations. It is similar to the perturbation expansion in that it assumes the knowledge of the eigenvalues and eigenstates of some related (unperturbed) system. However, unlike perturbation expansion, LRM produces correct results however large the modification of the original system. LRM of finite-dimensional systems is here generalized to the combined (external and internal) modifications. Parent n-dimensional system A n containing n eigenvalues λ i and n eigenstates \({| {\Phi_i}\rangle}\) is described by the generalized n × n eigenvalue equation. In an external modification system A n interacts with another ρ-dimensional system B ρ which is situated outside the system A n . In an internal modification relatively small σ-dimensional subsystem of the parent system A n is modified. Modified system C n+ρ that contains external as well as internal modifications is described by the generalized (n + ρ) × (n + ρ) eigenvalue equation. This system has (n + ρ) eigenvalues \({\varepsilon_s}\) and (n + ρ) corresponding eigenstates \({| {\Psi_s}\rangle}\) . In LRM this generalized (ρ + n) × (ρ + n) eigenvalue equation is replaced with a (nonlinear) (ρ + σ) × (ρ + σ) equation which produces all eigenvalues \({\varepsilon_s \notin \left\{ {\lambda_i}\right\}}\) and all the corresponding eigenstates \({| {\Psi_s}\rangle }\) of C n + ρ. Another equation produces remaining solutions (if any) that satisfy \({\varepsilon_s \in \left\{ {\lambda_i}\right\}}\) . Those two equations produce exact solution of the modified system C n + ρ. If (ρ + σ) is small with respect to n, this approach is numerically much more efficient than a standard diagonalization of the original generalized eigenvalue equation. Unlike perturbation expansion, LRM produces exact results, however large modification of the parent system A n . 相似文献
37.
An efficient strategy for the oxidative carbonylation of aromatic amides via C-H/N-H activation to form phthalimides using an Rh(III) catalyst has been developed. The reaction shows a preference for C-H bonds of electron-rich aromatic amides and tolerates a variety of functional groups. 相似文献
38.
39.
A highly diastereoselective Lewis acid-mediated [1,3] rearrangement of 1,3-dioxepins is the key step along a modular route to 2,3,4-trisubstituted tetrahydrofurans. 相似文献
40.
Jeroen G. Burgers Christiaan L. M. Mantz Tomislav Prokopec 《General Relativity and Gravitation》2013,45(1):155-187
We construct the gauge invariant potentials of Hermitian Gravity [1] and derive the linearized equations of motion they obey. A comparison reveals a striking similarity to the Bardeen potentials of general relativity. We then consider the response to a point particle source, and discuss in what sense the solutions of Hermitian Gravity reduce to the Newtonian potentials. In a rather intriguing way, the Hermitian Gravity solutions exhibit a generalized reciprocity symmetry originally proposed by Born in the 1930s. Finally, we consider the trajectories of massive and massless particles under the influence of a potential. The theory correctly reproduces the Newtonian limit in three dimensions and the nonrelativistic acceleration equation. However, it differs from the light deflection calculated in linearized general relativity by 25 %. While the specific complexification of general relativity by extension to Hermitian spaces performed here does not agree with experiment, it does possess useful properties for quantization and is well-behaved around singularities as described in [1]. Another form of complex general relativity may very well agree with experimental data. 相似文献